1. Field of the Invention.
This invention relates to novel reactive coatings which can be cured at room temperature or force dried at temperatures ranging up to about 350.degree. F. The coatings may be utilized as primers, topcoats or as clearcoats and/or basecoats in clearcoat/basecoat compositions. The combination of carboxylic acid-functional compounds, anhydride-functional compounds, epoxy-functional compounds and hydroxy-functional compounds provides fast reacting, durable coatings which minimize the toxicity problems which may be associated with other low temperature curing systems.
2. Description of the Prior Art.
One common prior art approach to high performance low temperature curing coatings has involved two-component coatings comprising reactive isocyanates and active hydrogen-containing compounds such as hydroxyl-containing polymers or amine-containing polymers to produce polyurethane or polyurea coatings. Although these materials have excellent performance and cure at low temperatures, the isocyanates may, under some conditions, be relatively hazardous to handle.
Coating compositions comprising reactive combinations of epoxy-containing compounds and compounds having acid or amine functionality are known in the art. Similarly, coating compositions comprising cyclic anhydrides and hydroxy-functional compounds are also known in the art. The prior art has not, however, taught the combination of anhydride-functional compounds, acid-functional compounds, epoxy-functional compounds and hydroxy-functional compounds to provide low temperature curing coatings having excellent durability and performance.